Image forming process and apparatus

Abstract

A developing agent comprises an insulative toner and a conductive carrier, and the tensile rupture stress of the insulative toner powder layer is 0.1-1 g wt/cm2. The insulative toner used is insulative magnetic toner to which hydrophobically treated inorganic particles and conductive particles have been externally added.

We claim: 
     
       1. An image forming process, using an apparatus comprising a photoconductor formed by successive laminations of a conductive layer of a light-transmittable material and a photoconductive layer on a substrate, a light source arranged on the substrate side of said photoconductor, and a developing roll arranged on the photoconductive layer side of said photoconductor, said process comprising the steps of: relatively moving said photoconductor with respect to said developing roll, by which a developing agent present around said developing roll contacts said photoconductor in an area of said photoconductor near said developing roll;   electrically charging said photoconductor through said developing agent in said area by applying a voltage between said photoconductor and said developing roll;   exposing said photoconductor in said area with a light image by said light source to form a latent image on said photoconductor;   developing said latent image on said photoconductor with said developing agent in said area to form a developed image on said photoconductor; and   transferring said developed image from said photoconductor to a recording medium;   wherein said developing agent comprises an insulative toner and a conductive carrier, said insulative toner being a non-magnetic toner, the tensile rupture stress of a layer of the insulative toner powder is 0.1 to 1 gf/cm 2 , and said photoconductor further comprises a surface insulating layer on the surface thereof, said surface insulating layer further containing a compound which charges to the same polarity as the toner with respect to said carrier.   
     
     
       2. The image forming process of claim 1, characterized in that insulative organic or inorganic fine particles are externally added to said insulative toner, and the coating ratio of the fine particles on the toner surface is in a range of 0.5 to 1. 
     
     
       3. The image forming process of claim 1, characterized in that the volume resistance of said developing agent is 10 10  Ω·cm or lower. 
     
     
       4. The image forming process of claim 1, characterized in that said insulative toner further comprises conductive particles externally added to said insulative toner so that said toner is semi-conducting. 
     
     
       5. The image forming process of claim 4, wherein the electrical resistance of said conductive particles is 10 5  Ω·cm or lower. 
     
     
       6. The image forming process of claim 4, wherein the particle size of said conductive particles is 0.6 μm or less. 
     
     
       7. The image forming process of claim 4, characterized in that the loss permittivity of said insulative toner is 0.1 to 1. 
     
     
       8. The image forming process of claim 4, characterized in that said conductive particles comprise at least one selected from the group consisting of carbon, tin oxide-based composite oxide, conductive titanium oxide in which the surface of titanium oxide is treated with a tin oxide-based semiconductor, and conductive barium sulfate in which the surface of barium sulfate is treated with a tin oxide-based semiconductor. 
     
     
       9. The image forming process of claim 4, wherein said conductive particles are added in an amount of 1 wt % or less with respect to the weight of the toner. 
     
     
       10. The image forming process of claim 4, wherein said conductive particles are magnetite added in an amount of 1 wt % or less with respect to the weight of the toner.